ch_36_skeletal_muscular_integumentary_system.ppt - Skeletal...

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Unformatted text preview: Skeletal, Muscular, and Integumentary System Ms. Louis Biology Class Skeletal System The Skeletal system is support system of the body, much like the wooden frame of a house. The human skeletal is composed of a type of connective tissue – bone. Bone, cartilage and ligaments-form the skeletal system. The Skeleton The skeletal system many important functions: Supports the body Protects internal organs Provides for movement Stores mineral reserves Site for blood cell formation Bones protect the delicate internal organs--the skull protects the brain; the ribs form a cage that protect the heart and lungs. provide a system of levers on which muscles act to produce movement. Levers—are rigid rods that move at a fixed point. contain reserves of minerals---calcium salts--that are important to many body processes are the site of blood cell formation---soft marrow tissue that fills the internal cavities in some bones. Bones There are 206 bones in the adult skeleton. These bones are divided into two parts--the axial skeleton and the appendicular skeleton o o The axial skeleton supports the central axis of the body--- the skull, the vertebral column, and the rib cage. The appendicular skeleton consists of the arms and leg bones, along with bones of the pelvis and shoulder area. Structure of Bones Bones are living cells and proteins fibers that are surrounded by deposits of calcium salts. Periosteum (pehr –ee-ahs-teeum)--- the tough layer of connective tissue surrounding the bone blood vessels pass through the periosteum carry oxygen and nutrients to the bone. Structure of Bones (cont’d) Compact bone---the thick layer beneath the periosteum; it’s dense but not solid . o Haversian (huh-VUR-zhun) canals---a network of tubes running through compact bone that contains blood vessels and nerves. Spongy bone---less dense tissue found inside the outer layer of compact bone; it’s found the end of long bones and in the middle of short, flat bones. Structure of Bones (cont’d) Bone cells --Osteocytes ---mature bone cells; embedded in the bone matrix Osteoclasts and osteoblasts ---line the Haversian canals and the surfaces of compact and spongy bone. Osteoclasts ---break down bone; osteoblasts---produce bone. Structure of Bones (cont’d) Bone Marrow --Inside bones are cavities that contain a soft tissues---bone marrow There are two types of bone marrow: yellow and red marrow Yellow marrow--- made up of fat cells Red marrow ---produces red blood cells (RBC), some white blood cells, and platelets. Development of Bones The skeleton of an embryo is composed almost entirely of cartilage ---a type of connective tissue. Cartilage is replaced by bone during ossification ---the process if bone formation. Types of Joints Joints ---are where one bone attaches to another bone and permit bones to move with out damaging each other Joints are classified depending on its type of movement Immovable joints Immovable joints, or fixed joints---allow no movement; bones are interlocked and fused together. Ex.: skull Slightly Movable joints o o Slightly Movable joints-- permit a small amount of restricted movement; bones are separated from each other. Ex. lower leg; adjacent vertebrae and pelvic bone Freely Movable joints Freely Movable joints--- permit movement in one or more directions. The most common types of Freely Movable joints: Freely Movable joints (cont’d) Ball-and-socket Joint--movement in multiple directions Hinge Joint--back-and-forth motion, like a door Freely Movable joints (cont’d) Pivot Joint ---allows one bone to rotate around another Saddle Joint ---one bone to slide in two directions Structure of Joints cartilage covers the surface where two bones come together they are surrounded by a two-layer joint capsule that helps to hold the bone and still allow them to move: Structure of Joints ligaments ---first layer of the joint capsule forms strips of tough connective tissue that holds bones together in a joint synovial fluid ---produced by cells in the other layer— this forms a thin film on the cartilage---in the knee small sacs of synovial fluid called bursae form. The Muscular System The Muscular System Movement is the primary function of the muscular system. There are three different types of muscle tissue: Skeletal Smooth Cardiac Types of Muscle Tissue Skeletal Muscles are attached to bones they are responsible for voluntary movements they appear to have alternating light and dark bands called striations they are consciously controlled by the CNS. Types of Muscle Tissue (cont’d) Smooth Muscles Smooth Muscles are not under voluntary control located in the walls of hollow structures such as the stomach, blood vessels, and intestines move food through the digestive track can function without nervous stimulation Types of Muscle Tissue (cont’d) Cardiac Muscle-- is found in the heart is striated is not under the direct control of the CNS Control of Muscle Contraction Muscles contract when the thin filaments in the muscle fiber slide over the thick filaments. Motor neurons connect the CNS to skeletal muscle cells Motor neurons control the contractions of skeletal muscle fibers Control of Muscle Contraction Neuromuscular junction--- the point of contact between a motor neuron and a skeletal muscle cell Vesicles in the axon terminals of the motor neuron release a neurotransmitter called acetylcholine Acetylcholine diffuse across the synapse producing an impulse in the muscle fiber which causes the release of calcium ions within the fiber Control of Muscle Contraction Calcium ions affect the proteins that allow actin and myosin to interact. It only takes a few milliseconds before these events to occur and the muscle cell contracts. How Muscles and Bones Interact Skeletal muscles are joined to bones by tendons. Tendons pull on the bone and make them work like levers and the joint functions as a fulcrum ---the fixed point around which the lever moves. Muscles provide the force that moves the lever. Most muscles work in opposing pairs . Ex., when the biceps contract the triceps are relaxed, and vice versa. Integumentary System Skin, the single largest organ of the body, is part of the integumentary system Skin, hair, nails, and a variety of glands--make up the integumentary system The Integumentary system functions are: serves as a barrier against infection and injury helps to regulate body temperature removes waste products from the body provides protection against ultraviolet radiation from the sun The Skin The Skin most important function is protection contains several sensory receptors---serves as the gateway where sensations like pressure, heat, cold, and pain are transmitted to the nervous system. is made of two main layers---the epidermis and the dermis---beneath the dermis is a subcutaneous layer of fat (hypodermis) and loose connective tissue that help insulate the body. Epidermis the outer layer of the skin is the epidermis--- has two layers the outside of the epidermis that comes in contact with the environment---is made up of dead cells; the inner layer is made up of living cells inner layer cells of the epidermis undergo rapid cell division---the new cells push the older cells to the surface of the skin as they move up, older cells becomes flattened, their organelles disintegrate, and they begin making keratin---a tough, fibrous protein. Epidermis (cont’d) keratin cells eventually die and form a tough, flexible, waterproof covering on the surface of the skin The outer layer of dead cells is shed/washed away once every four to five weeks contains melanocytes---cells that produce melanin---a dark brown pigment, that helps protect the skin from damage from the sun has no blood vessels Dermis the inner layer of the skin is the dermis---contains collagen fibers, blood vessels, nerve endings, glands, sensory receptors, smooth muscles, and hair follicles. The skin interacts with other body systems to maintain homeostasis by helping to regulate body temperature. When it’s cold the blood vessels in the dermis are narrow, limiting heat loss; on hot days the blood vessels widen, increasing heat loss. Contains two major types of glands: sweat glands---produce perspiration when your body gets too hot sebaceous glands (oil glands)---produce sebum---an oily secretion—spreads along the surface of the skin and keep the keratin-rich epidermis flexible and waterproof. Hair the basic structure of human hair and nails is keratin. Hair has important functions: on the head protects the scalp from UV light and insulates from the cold in the nostrils, outside ear canals, and around the eyes prevents dirt from entering the body hair is produced at the base of structures called hair follicles---are tube like pockets of epidermal cells that extend into the dermis Nails Nails grow from the nail root—located at the tips of fingers and toes Nails covers and protects the tips of fingers and toes; grows at an average of 3mm per month. ...
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